. >>> new chapter in the search for jimmy hoffa. police broke through concrete in michigan today. their findings ahead. >>> the families of several students in minnesota are suing the school and a former teacher who they say segregated african-american and white students in his classroom. the teacher had other incidents of questionable behavior on his record dating back several years and even though he's not in the classroom anymore, he is still collecting checks. gary tuchman investigated. >> reporter: it's the middle of the school day and this sixth grade teacher is riding a motorcycle. the reason timothy olmstead is not in school is complex and according to many, deeply disturbing. 12-year-old alicia jones was one of his students. >> he separated me from the white kids and sent me to the other side of the room where all the black kids were. >> reporter: timothy olmstead is accused by students and their families of taking black children and disabled children at the heights community school in st. paul, minnesota, and segregating them from white children. melissa dobbs was also a